1. Field of the Invention
The present invention relates to an electrical drive device which is provided for a bending photographing optical system and which electrically drives at least one optical element of the bending photographing optical system.
2. Description of the Related Art
In order to slim down an imaging apparatus, a bending photographing optical system which provides a prism(s), which bends the optical axis, in the optical path of the photographing optical system, is known in the art. Furthermore, photographing apparatuses which electrically drive an optical element (typically a lens element) positioned in the optical path in order to perform a focusing operation and/or a zooming operation have also become well-known in the art.
In an imaging apparatus which is provided with such a bending photographing optical system and which electrically drives an optical element that is provided in the optical path thereof, in order to achieve further miniaturization, it has been proposed in Japanese Unexamined Patent Publication No. 2007-121494 to provide an electrical drive motor behind (at the other side of) the reflection surface of the prism (namely, at a position overlapping the reflection surface when viewing the reflection surface in a direction along the incident light-rays/exit light-rays).
In the above-mentioned Japanese Unexamined Patent Publication No. 2007-121494, by providing the electrical drive motor behind (at the other side of) the reflection surface of the prism, a certain degree of miniaturization of the imaging apparatus can be achieved. However, according to the inventors of the present invention, the miniaturization achieved in the above-mentioned Japanese Unexamined Patent Publication is insufficient, especially in regard to the reduction in the width in a direction orthogonal to the direction of the optical axis (i.e., the width in a direction orthogonal to a plane on which the incident optical axis and the exit optical axis of the prism lie) of the bending photographing optical system.